Ok I'm going to answer my own question, but it might help others. I've researched and it says that it can damage a dogs kidneys. If you feed grapes or raise to a dog 1oz of fruit per 2.2 lbs of body wt. Symptoms are vomiting, diarrhea, lack of appetite, lethargy,and abdominal pain. You should call your vet immediately if any of these symptoms arise and induce vomiting.
Wow, I didn't know that either. So how come it is not toxic to us humans? Dogs eat off the ground etc. I am glad to learn this. I thought it would just make the dog have to go to the bathroom and clean him/her out. I would ask your vet for sure. I have never heard of this til now.
It could make there liver stop working.
Depends on the individual dog and their sensitivity. Only one may be okay but they are toxic. Just like even large dogs have died from so much as licking an ice cube that had been in an alcoholic drink but others have not. Should probably be okay if your pup accidentally eats one grape but you should still be vigilant. :-). Poisoning doesn't always show symptoms right away or even for a few days or a week. If your pup accidentally eats grapes or more than one you may want to call your vet just to be safe and see what they think after learning the details.